Tuning the optoelectronic properties of ZOPTAN core-based derivatives by varying acceptors to increase efficiency of organic solar cell

Efficient side-chain engineering of thieno-imidazole salt-based molecule to boost the optoelectronic attributes of organic solar cells: A DFT approach

This study focused on modeling and density functional theory (DFT) analysis of reference (AI1) and designed structures (AI11-AI15), based on the thieno-imidazole core, in order to create profitable candidates for solar cells. All the optoelectronic properties of the molecular geometries were computed using DFT and time dependent-DFT approaches. The influence of terminal acceptors on the bandgaps, absorption, hole and electron mobilities, charge transfer capabilities, fill factor, dipole moment, etc. Of the recently designed structures (AI11-AI15), as well as reference (AI1), were evaluated. Optoelectronics and chemical parameters of newly architecture geometries were shown to be superior to the cited molecule. The FMOs and DOS graphs also demonstrated that the linked acceptors remarkably improved the dispersion of charge density in the geometries under study, particularly in AI11 and AI14. Calculated values of binding energy and chemical potential confirmed the thermal stability of the molecules. All the derived geometries surpassed the AI1 (Reference) molecule in terms of maximum absorbance ranging from 492 to 532 nm (in chlorobenzene solvent) and a narrower bandgap ranging from 1.76 to 1.99eV. AI15 had the lowest exciton dissociation energy of 0.22eV as well as lowest electrons and hole dissociation energies, while AI11 and AI14 showed highest VOC, fill factor, power conversion efficiency (PCE), IP and EA (owing to presence of strong electron pulling cyano (CN) moieties at their acceptor portions and extended conjugation) than all the examined molecules, implying that they could be used to build elite solar cells with enhanced photovoltaic attributes.

Impact of various heterocyclic π-linkers and their substitution position on the opto-electronic attributes of the A-π-D-π-A type IECIO-4F molecule: a comparative analysis

To investigate the consequence of different substitution positions of various π-linkers on the photovoltaic properties of an organic solar cell molecule, we have introduced two series of six three-donor molecules, by the substitution of some effective π-linkers on the A-π-D-π-A type reference molecule IECIO-4F (taken as IOR). In series "a" the thienyl or furyl bridge is directly linked between the donor and acceptor moieties, while in series "b" the phenyl ring of the same bridge is working as the direct point of attachment. The frontier molecular orbitals, density of states, transition density matrix, molecular electrostatic potential surfaces, exciton binding energy, excitation energy, wavelength of maximum absorption, open-circuit voltage, fill factor, and some other photovoltaic attributes of the proposed molecules were analyzed through density functional theory (DFT) and its time-dependent (TD) approach; the TD-DFT method. Though both series of newly derived molecules were a step up from the reference molecule in almost all of the studied characteristics, the "a" series (IO1a to IO3a) seemed to be better due to their desirable properties such as the highest maximum absorption wavelength (λ max), open-circuit voltage, and fill factor, along with the lowest excitation and exciton dissociation energy, etc. of its molecules. Also, the studied morphology, optical characteristics, and electronic attributes of this series of proposed molecules signified the fact that the molecules with thienyl or furyl ring working as the direct link between the acceptor and donor molecules showed enhanced charge transfer abilities, and could provide a maximum quantum yield of the solar energy supplied.

Impact of end capped modification on BT-CIC molecule for high-performance photovoltaic attributes: a DFT approach

With the aim of utilizing structural modeling techniques to design efficient organic solar cells, a quantum chemical density functional theory (DFT) and its time-dependent DFT (TD-DFT) study have been carried out for the examination of the photovoltaic properties of four BT-ClC-based novel non-fullerene acceptor (NFA) molecules. The designed entities (BT1-BT4) have an A-π-D-π-A configuration with seven fused ring-based BDT central core and newly substituted peripheral acceptor moieties. The optical parameters (absorption maxima, light-harvesting efficiency, first excitation energies, and dipole moments), electronic properties (frontier molecular orbitals, density of states, and molecular electrostatic potential), and charge transfer characteristics (open-circuit voltage, transition density matrix, and fill factor) of the investigated molecules were evaluated using the selected B3LYP/6-31G (d,p) level of theory. The systematic computational analysis reveals that under the influence of terminal acceptor groups, there is an augmentation in the absorption range, and reduction in the band gap values. The electron withdrawing effect of acceptor moieties is evident from the electronic density distribution on the HOMO-LUMO orbitals, along with the density of state (DOS) graphs. Transition density matrix (TDM) analyses reveal consistent charge transfer in the newly devised entities. Reorganization energies computed for electron and hole are significantly lower than the reference, making the transfer of charge carriers efficient. Open-circuit voltage (V_oc) of reported acceptor entities, theoretically computed with PTB7-Th donor, revealed maximum output. Furthermore, the estimated fill factor (FF) of the investigated molecules predicted an increase in power conversion efficiencies. Consequently, all the computed parameters favor the applicability of our designed molecules in the field of organic photovoltaics by virtue of their excellent charge mobilities, increased absorption maximum values, and reduced band gaps.

DFT study of alkali and alkaline earth metal-doped benzocryptand with remarkable NLO properties

Strategies for designing remarkable nonlinear optical materials using excess electron compounds are well recognized in literature to enhance the applications of these compounds in nonlinear optics. In this study, density functional theory simulations are performed to study alkali and alkaline earth metal-doped benzocryptand using the B3LYP/6-31G+(d, p) level of theory. Vertical ionization energies (VIEs), reactivity parameters, interaction energies, and binding energies exposed the thermodynamic stability of these complexes. FMO analysis revealed that HOMO is located on alkali metals having polarized electrons, which are easy to excite. The doping strategy enhanced the charge transfer with low bandgap energy in the range of 0.68-2.23 eV, which is lower than that of the surface BC (5.50 eV). Also, the lower transition energies and higher oscillator strength indicate that these complexes exhibit excellent electronic and optical properties. Non-covalent interaction analysis suggested the presence of van der Waals interactions between dopants and surface. IR analysis provided information about the frequencies of stretching vibrations present in the complexes due to different bonds. UV-vis analysis revealed that all the newly designed excess electron complexes are transparent in the UV region and possessed maximum absorption in the visible and NIR region, ranging from 753.6 to 2150 nm, which is higher than the surface (244 nm). Thus, these complexes have a potential for high-performance NLO materials in the applications of optics. Natural bond orbital analysis (NBO), transition density matrix (TDM), electron density difference map (EDDM), and density of state (DOS) analyses were also performed to study the charge transfer properties. Moreover, these complexes possessed remarkable optoelectronic properties due to a significant increase in the isotropic linear polarizability (α iso) in the range of 629.59-1423.23 au. Further, these systems demonstrated an extraordinary large total first hyperpolarizability (β tl) in the range of 3695.55-910 706.43 au. The rationalization of hyperpolarizability by the two-level model reflected a noteworthy increase in β tl because of low transition energies (ΔE) and high transition dipole moment (Δμ). Thus, our results showed that alkali and alkaline earth metal-doped BC might be a competitor for efficient nonlinear optical properties with practical applications in the area of optoelectronics.

Symmetrical end-capped molecular engineering of star-shaped triphenylamine-based derivatives having remarkable photovoltaic properties for efficient organic solar cells

In the present research work, four novel triphenylamine (TPA)-based acceptor molecules have been architectured to step up the solar efficiency of organic solar cells. The four designed molecules abbreviated as T1-T4 have a common TPA donor core and different strong electron pulling peripheral acceptor groups connected through thiophene spacers. Computational simulations of T1-T4 were performed to compute and compare their optoelectronic properties with well-known reference molecule S(TPA-DPP) designated as R in the current project. For geometric optimizations of designed molecules, MPW1PW91 functional along with a basis set of 6-31G (d, p) was enforced. Assessment of the optoelectronic features of newly reported 3-D molecules (T1-T4) has been executed through density functional theory (DFT) and time-dependent density functional theory (TD-DFT) computations. Transition density matrix (TDM) and density of state (DOS) evaluations were performed for the investigation of exciton dynamics and electronic contribution between two states. All the derived molecules exhibited admirable photovoltaic features when compared to that of the reference molecule. Amidst all these newly modified molecules, T3 manifested itself as the finest candidate having the least energy band gap (1.84 eV) and the highest λ_max (865 nm) in dichloromethane solvent. Also, T1 molecule has the lowest hole reorganization energy (0.0036 eV) value. These designed candidates (T1-T4) confirm that peripheral acceptor tempering is an effectual approach for the attainment of the desirable optoelectronic properties.